1. PROJECTIONS OF SOLIDS
Part III
Prof.T.JEYAPOOVAN
Department of Mechanical Engineering
Hindustan Institute of Technology and Science
Chennai-603103, India
www.EGlive.in
2. Projections of a Solid kept with its axis
inclined to VP and parallel to HP
• Whenever the axis of the solid is kept inclined
to VP and parallel to HP, the projections of the
solid is drawn using the following methods.
– Change of position method
– Change of reference line method
• Change of position method is simple and
commonly used to draw the projections.
www.EGlive.in
3. Change of position method
• Change of position method has 2 steps
• Step 1: Assume the axis of the solid is kept
perpendicular to VP and parallel to HP, draw
the FV and project the TV.
• Step 2: Reproduce the TV obtained in STEP 1
to the required inclination of the axis with XY
and project the FV. Show the visible and hidden
edges to complete the projections.
www.EGlive.in
4. Example 1: A pentagonal prism of base side 30 mm axis length 60
mm is resting on HP on one of its rectangular faces with its axis
inclined at 40° to VP. Draw its projections.
• Step1: Assume the axis
perpendicular to VP and
parallel to HP. Draw the
FV and project the TV.
• Step 2: Reproduce the TV
of STEP 1 at 40º to XY
and project the FV. Show
the visible and hidden
edges to complete the
projections.
www.EGlive.in
5. Example 2: Draw the projections of a cylinder 60 mm diameter and
75 mm long, lying on the ground with its axis inclined at 60º to VP.
Draw its projections.
• Step1: Assume the axis
perpendicular to VP and
parallel to HP. Draw the FV
and project the TV. Divide
the circle into 8 equal parts
to show 8 generators.
• Step 2: Reproduce the TV
of STEP 1 at 60º to XY and
project the FV. Show the
visible and hidden edges to
complete the projections.
www.EGlive.in
6. Example 3: A hexagonal pyramid of base side 30 mm and axis
length 60 mm is resting on VP on one of its triangular faces with its
axis parallel to HP. Draw its projections.
• Step1: Assume the axis
perpendicular to VP and
parallel to HP. Draw the FV
and project the TV. Note that
one of the sides of the
hexagon is taken
perpendicular to XY.
• Step 2: Reproduce the TV of
STEP 1 and project the FV.
Show the visible and hidden
edges. Note that one of the
triangular faces is on VP.
www.EGlive.in
7. Example 4: A cone of base diameter 50 mm and axis length 60 mm
is resting on VP on one of its generators with its axis parallel to HP.
Draw its projections.
• Step1: Assume the axis
perpendicular to VP and
parallel to HP. Draw the FV
and project the TV. Divide the
circle into 8 equal parts to
show 8 generators.
• Step 2: Reproduce the TV of
STEP 1 such that one of the
generators is on XY and
project the FV. Note that
generators are shown in thin
lines.
www.EGlive.in
8. Tips to Mark Visible and
Hidden Edges
• Read the problem carefully and understand the 2 steps.
Draw the polygon in first step of FV and project TV, then
follow the second step.
• The base corners, edges and longer edges marked on and
above the axis of the solid in front view are always
visible in top view, other portion is invisible.
• Outer or boundary edges of top or front views are always
visible.
www.EGlive.in
9. REFERENCE BOOKS
1. Jeyapoovan T, “Lesson Plans for Engineering
Graphics”, 2010, Vikas Publishing House Pvt
Ltd, New Delhi.
2. Jeyapoovan T, “Engineering Drawing and
Graphics”, 2011, Vikas Publishing House Pvt
Ltd, New Delhi.
www.EGlive.in